Plateosaurus

Plateosaurus is a prosauropod (early sauropodomorph) dinosaur genus from the Late Triassic, and existed between 214 and 204 million years ago. It was discovered by Johann Friedrich Engelhardt in 1834, at Heroldsberg near Nuremberg, Germany, and scientifically described by Mermann von Meyer in 1837[1]. The meaning of its name is „broad lizard”. The type species was originally P. engelhardti, but it was replaced with P. trossingensis by the ICZN (International Code of Zoological Nomenclature) in 2019, as P. engelhardti was undiagnostic. We know its fossils from North and Central Europe, and from Greenland. Plateosaurus is one of the best known dinosaurs, and up to now more than 100 skeletons have been found, some of them are almost complete[2]. The three most important localities are near Halberstadt in Saxony-Anhalt, Germany; Trossingen in Baden-Württemberg, Germany; and Frick, Switzerland[2].

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Known occurrences of Plateosaurus fossils.

Valid species

Recently we know three scientifically valid species in the genus: P. trossingensis, P. longiceps, and P. gracilis.

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Plateosaurus. Source: By Nobu Tamura (http://spinops.blogspot.com) - Own work, CC BY 3.0, https://commons.wikimedia.org/w/index.php?curid=19459004

Description and anatomy

Plateosaurus was a bipedal dinosaur with long neck and small head, strong hind-limbs, short but powerful arms and three-fingered grasping hands with large claws. Plateosaurus was a digitigrad animal – it walked on its toes[3]. It might have used its claws for feeding and defence. Its tail was muscular and had a high mobility[4]. Adults ranged between 4.8 and 10 meters[5] and weighed between 600 and 4000 kilograms [4], and usually have lived for 12 to 20 years. It had numerous small, leaf-shaped, blunty serrated, and socketed teeth, which was used for crushing plant material[6]. The position of the jaw joint allow to conclude that Plateosaurus might give a very powerful bite[7]. This dinosaur probably had all-around vision, with its eyes directed to the two sides of the animal, allowing it effectively watch for predators[3][6][7]. Some fossils have preserved the sclerotic rings, which gave protection for the eyes[3][6][7]. According to the newest scientiic evidences, it seems that Plateosaurus was endothermic[5][8]. Earlier some authors suggested that it might have been bipedal, walking on its hindlimbs[3], others that it was quadrupedal[5], or that it was able to switching between these two postures[9][10]. However, a recent detailed study of the forelimbs that proved that Plateosaurus was unable to pronate its hands, led to the final conclusion of Plateosaurus being an obligate bipedal dinosaur[11].

Paleobiology

Though Plateosaurus was a herbivorous dinosaur, it is likely that it supplemented its diet with small prey animals or carrion, which actually would make them omnivores[12].

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Plateosaurus skeleton. Source: By FunkMonk - Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=12380131

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Plateosaurus skull. Source: By philosophygeek from San Francisco, US - T. Rex HeadUploaded by FunkMonk, CC BY-SA 2.0, https://commons.wikimedia.org/w/index.php?curid=7984803

Scientific references

[1] Meyer, H. von (1837): Mitteilung an Prof. Bronn (Plateosaurus engelhardti) [message to Prof. Bronn (Plateosaurus engelhardti)]. Neues Jahrbuch für Geologie und Paläontologie (in German). 1837: 316.

[2] Sander, P.M. (1992): The Norian Plateosaurus bonebeds of central Europe and their taphonomy. Palaeogeography, Palaeoclimatology, Palaeoecology. 93 (3–4): 255–299. doi:10.1016/0031-0182(92)90100-J.

[3] Huene, F. von (1926): Vollständige Osteologie eines Plateosauriden aus dem schwäbischen Keuper [Complete osteology of a plateosaurid from the Swabian Keuper]. Geologische und Paläontologische Abhandlungen, Neue Folge (in German). 15 (2): 139–179.

[4] Mallison, H. (2010): The digital Plateosaurus II: an assessment of the range of motion of the limbs and vertebral column and of previous reconstructions using a digital skeletal mount. Acta Palaeontologica Polonica. 55 (3): 433–458. doi:10.4202/app.2009.0075.

[5] Sander, M.; Klein, N. (2005): Developmental plasticity in the life history of a prosauropod dinosaur. Science. 310 (5755): 1800–1802. doi:10.1126/science.1120125.

[6] Jaekel, O. (1911): Die Wirbeltiere. Eine Übersicht über die fossilen und lebenden Formen [The Vertebrates. An overview of the fossil and extant forms] (in German). Berlin: Borntraeger.

[7] Galton, P.M. (1984): Cranial anatomy of the prosauropod dinosaur Plateosaurus from the Knollenmergel (Middle Keuper, Upper Triassic) of Germany. I. Two complete skulls from Trossingen/Württ. With comments on the diet. Geologica et Palaeontologica. 18: 139–171.

[8] Klein, N.; Sander, P.M. (2007). Bone histology and growth of the prosauropod dinosaur Plateosaurus engelhardti von Meyer, 1837 from the Norian bonebeds of Trossingen (Germany) and Frick (Switzerland). In Barrett, P.M.; Batten, D.J. (eds.). Evolution and Palaeobiology of Early Sauropodomorph Dinosaurs (Special Papers in Palaeontology 77). Oxford: Blackwell Publishing. pp. 169–206.

[9] Galton, P.M. (1990): Basal Sauropodomorpha-Prosauropoda. In Weishampel, D.B.; Dodson, P.; Osmólska, H. (eds.). The Dinosauria (1 ed.). Berkeley: University of California Press. pp. 320–344. ISBN 978-0-520-06727-1.

[10] Paul, G.S. (1997): Dinosaur models: the good, the bad, and using them to estimate the mass of dinosaurs. In Wolberg, D.L.; Stump, E.; Rosenberg, G. (eds.). Dinofest International: Proceedings of a Symposium held at Arizona State University. Philadelphia: Academy of Natural Sciences. pp. 129–154. ISBN 978-0-935868-94-4.

[11] Bonnan, M.; Senter, P. (2007): Were the basal sauropodomorph dinosaurs Plateosaurus and Massospondylus habitual quadrupeds?. In Barrett, P.M.; Batten, D.J. (eds.). Evolution and Palaeobiology of Early Sauropodomorph Dinosaurs (Special Papers in Palaeontology 77). Oxford: Blackwell Publishing. pp. 139–155. ISBN 978-1-4051-6933-2.

[12] Barrett, P.M. (2000): Prosauropod dinosaurs and iguanas: Speculations on the diets of extinct reptiles. In Sues, H.-D. (ed.). Evolution of Herbivory in Terrestrial Vertebrates: Perspectives from the Fossil Record. Cambridge: Cambridge University Press. pp. 42–78. ISBN 978-0-521-59449-3.